Negative refraction occurs at interfaces as a natural consequence of the negative group velocity of waves in one of the interfacing media. The historical origin of this understanding of the phenomenon is briefly discussed. We consider several physical systems that may exhibit normal electromagnetic waves (polaritons) with negative group velocity at optical frequencies. These systems are analyzed in a unified way provided by the spatial dispersion framework. The framework utilizes the notion of the generalized dielectric tensor eij(ω, k) representing the electromagnetic response of the medium to perturbations of frequency ω and wave vector k. Polaritons with negative group velocity can exist in media (whether in natural or in artificial meta-materials) with a sufficiently strong spatial dispersion. Our examples include both gyrotropic and nongyrotropic systems, and bulk and surface polariton waves. We also discuss the relation between the spatial dispersion approach and the more familiar, but more restricted, description involving the dielectric permittivity e(ω) and the magnetic permeability μ(ω) .

http://iopscience.iop.org/article/10.1070/PU2006v049n10ABEH006067/pdf

Spatial dispersion and negative refraction of light

The study of single crystal electrode surfaces by surface plasmon excitation

Studies of the surface state of solids, their detection, and studies of the surface transition layers including oxide films, physi-, and chemisorbed monomolecular films, their transformations at phase transitions and their chemical reactions have stimulated the development of a series of new methods. The nondestructive character of optical methods, their sensitivity to molecular structure and to the nature of chemical bonding, makes them very attractive for use.

Applications of Surface Polaritons for Vibrational Spectroscopic Studies of Thin and Very Thin Films

Optical bulk and surface waves with negative refraction

Diffraction methods in the spectroscopy of thin films in the vicinity of resonances

2014 The effects of very thin Ag surface layers on the propagation of surface plasma waves (S.P.W.) excited by ATR at an Al surface are investigated in the vicinity of the Ag plasma frequency and the S.P.W. dispersion relations, are obtained. A splitting of the dispersion curves is found for Ag layers 26, 39 and 58 Å thick, but does not appear for thinner layers. Experimental and computed dispersion curves are compared. LE JOURNAL DE PHYSIQUE TOME 39, JUIN 1978,

T. Lopez-Rios

Papers

Splitting of the Al surface plasmon dispersion curves by Ag surface layers